Various types of plastic tubing can include a relatively thin wall with a helical reinforcement. Such corrugated tubing can provide crush resistance while leaving the tubing flexible enough to allow for short-radius bends without collapsing or kinking the tubing. The versatility of this kind of tubing is evidenced by its use in construction, ventilation, manufacturing processes, auto washes, hospitals, medical devices, and other areas.
For certain uses of the above-described tubing, such as for medical uses, it is also desired to provide interior and exterior surfaces mostly free of crevices to eliminate or reduce contaminates that may reside in such crevices. In the case of inhalation therapies such as those using CPAP (Continuous Positive Airway Pressure) and other breathing assistance methods, a smooth inner bore for the tubing is also desired to reduce flow resistance when airflow is conducted through the tubing.
To obtain relatively crevice-free interior and exterior surfaces, the above-described tubing can be manufactured by extruding a plastic strip or ribbon and helically wrapping the ribbon upon itself while molten to form a tubing wall. In such a manufacturing process, a winding or wrapping head with multiple cantilevered and rotationally driven mandrels or winding rolls can be spaced about a longitudinal axis for winding and rotationally advancing helically wound tubing. In some examples, at least one wire and a thermoplastic reinforcement can be placed on the tubing wall while the tubing wall is formed. In such examples, the thermoplastic reinforcement heat bonds to the tubing wall. The tubing is then cooled to solidify before being cut into predetermined lengths.